In recent years, digital still cameras, digital mirrorless cameras, etc. using a solid-state imaging device such as a CCD (Charged Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor) have spread rapidly. The spread of such digital cameras, etc. leads to higher demand of a high performance imaging lens corresponding to the large number of pixels. Furthermore, such demand has been recently increasing not only for a zoom lens but also for a single focal lens having a fixed focal length.
Such a single focal lens is expected, as a need, to have a high-performance large aperture lens having maximum aperture of approximately F/1.4. Such an imaging lens is known, for example, as imaging lens systems disclosed in PTL 1 and PTL 2. The imaging lens system disclosed in PTL 1 is a single focal lens having a half angle of view of approximately 6° to 9° and maximum aperture of approximately F/2.0 to F/2.8. The single focal lens is characterized by including a first group having positive or negative refractive power, a second group having positive refractive power, and a third group having positive or negative refractive power, which are arranged from the object side thereof, in which the second group moves, on the optical axis, to perform focusing an object at a short distance. The imaging lens system disclosed in PTL 2 is a single focal lens having a half angle of view of approximately 14° and maximum aperture of approximately F/1.4. The single focal lens is characterized by including a first group having positive refractive power and a second group having positive refractive power, which are arranged from the object side thereof, in which the second group moves, on the optical axis, to focus an object at a short distance.